0297 Relationship Between Sleepiness Symptoms Questionnaire Ratings and Psychomotor Vigilance Performance in a Total Sleep Deprivation Study

Abstract

Abstract Introduction While measuring the neurobehavioral consequences of sleepiness is arguably best done with performance tasks providing objective assessments of impairment, this often proves challenging in real-world operational settings. Self-report instruments measuring subjective sleepiness provide a practical alternative, but field studies generally fail to show high correlation between objective and subjective assessments of impairment. The Sleepiness Symptoms Questionnaire (SSQ) is a self-report instrument developed to address this issue by asking about observable symptoms of sleepiness and (motor vehicle driving) performance impairment. In a laboratory sleep deprivation study, we compared SSQ sleepiness ratings to performance impairment on a 10min psychomotor vigilance test (PVT). Methods N=12 healthy normal sleepers (ages 21-39y, 6 females) participated in a 4-day in-laboratory study. After a baseline day (9h time in bed; 22:00-07:00), subjects underwent 38h total sleep deprivation (TSD) followed by a recovery day (9h time in bed; 22:00-07:00). As part of neurobehavioral testing throughout the experiment, subjects completed the SSQ and PVT back to back at 6.5h, 14.5h, 22.5h, and 30.5h TSD, and 6.5h after recovery sleep. Data from one subject were incomplete and discarded prior to analysis. Results As TSD progressed, the SSQ sleepiness ratings and the number of lapses (RTs>500ms) on the PVT were elevated, with sleepiness and performance impairment peaking at 22.5h TSD. Both measures returned to baseline levels after recovery sleep. Mixed-effects analysis of covariance showed moderate correlation between SSQ ratings and PVT lapses (r=0.44, F1,43=24.1, p<0.001). Conclusion Self-reported sleepiness on the SSQ reflected the expected homeostatic and circadian changes in sleep pressure during TSD and following recovery sleep, as did PVT performance impairment. The moderate correlation between subjective ratings on the SSQ, with its emphasis on observable sleepiness symptoms, and objective impairment on the PVT suggests that the SSQ may be a reasonably reliable instrument for measuring sleepiness under conditions of acute sleep deprivation. Support Jazz Pharmaceuticals